We are continuing the sequence analysis of the rabbit globin mRNAs. These sequences have now been cloned on bacterial plasmids so that we can use the rapid "ladder" sequencing techniques. The cDNA cloning technique is also being used to clone other mRNA sequences for comparative studies. Gene enrichment techniques are being developed to permit cloning of entire globin gene clusters. BIBLIOGRAPHIC REFERENCES: Appendix I: Salser, W., Bowen, S., Browne, D., El Adli, F., Fedoroff, N., Fry, K., Heindell, H., Paddock, G., Poon, R., Wallace, B. and Whitcome, P. (1976), "Investigation of the organization of mammalian chromosomes at the DNA sequence level," Federation Proceedings 35, 23-35. Appendix II: Higuchi, R., Paddock, G., Wall, R. and Salser, W. (1976), "A general method for cloning eukaryotic structural gene sequences," Proc. Nat. Acad. Sci. USA 73.